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13 pages, 2317 KiB

Open AccessArticle

Cobalt-Mediated Radical Copolymerization of Vinylidene Fluoride and 2,3,3,3-Trifluoroprop-1-ene

by Panagiotis G. Falireas and Bruno Ameduri

Polymers 2021, 13(16), 2676; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13162676 - 11 Aug 2021

Cited by 2 | Viewed by 1926

New copolymers based on vinylidene fluoride (VDF) and 2,3,3,3-tetrafluoroprop-1-ene (1234yf) were synthesized by organometallic-mediated radical copolymerization (OMRcP) using the combination of bis(tert-butylcyclohexyl) peroxydicarbonate initiator and bis(acetylacetonato)cobalt(II), (Co(acac)₂) as a controlling agent. Kinetics studies of the copolymerization of the fluoroalkenes [...] Read more.

New copolymers based on vinylidene fluoride (VDF) and 2,3,3,3-tetrafluoroprop-1-ene (1234yf) were synthesized by organometallic-mediated radical copolymerization (OMRcP) using the combination of bis(tert-butylcyclohexyl) peroxydicarbonate initiator and bis(acetylacetonato)cobalt(II), (Co(acac)₂) as a controlling agent. Kinetics studies of the copolymerization of the fluoroalkenes copolymers were monitored by GPC and ¹⁹F NMR with molar masses up to 12,200 g/mol and dispersities (Đ) ranging from 1.33 to 1.47. Such an OMRcP behaves as a controlled copolymerization, evidenced by the molar mass of the resulting copolymer-monomer conversion linear relationship. The reactivity ratios, r_i, of both comonomers were determined by using the Fineman-Ross and Kelen-Tüdos fitting model leading to r_VDF = 0.384 ± 0.013 and r_1234yf = 2.147 ± 0.129 at 60 °C, showing that a lower reactivity of VDF integrated in the copolymer to a greater extent leads to the production of gradient or pseudo-diblock copolymers. In addition, the Q (0.03) and e (0.06 and 0.94) parameters were assessed, as well as the dyad statistic distributions and mean square sequence lengths of PVDF and P1234yf. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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10 pages, 1864 KiB

Open AccessArticle

Synthesis and Thermal Degradation Study of Polyhedral Oligomeric Silsesquioxane (POSS) Modified Phenolic Resin

by Degang Wang, Jie Ding, Bing Wang, Yingluo Zhuang and Zhixiong Huang

Polymers 2021, 13(8), 1182; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13081182 - 07 Apr 2021

Cited by 12 | Viewed by 3770

Abstract

In this paper, a new polyhedral oligomeric silsesquioxane containing a phenol group (POSS-Phenol) is prepared through the Michael addition reaction, which is added to the synthesis of phenolic resin as a functional monomer. Infrared spectroscopy (IR) is used to demonstrate the chemistry structure [...] Read more.

In this paper, a new polyhedral oligomeric silsesquioxane containing a phenol group (POSS-Phenol) is prepared through the Michael addition reaction, which is added to the synthesis of phenolic resin as a functional monomer. Infrared spectroscopy (IR) is used to demonstrate the chemistry structure of the synthesized POSS modified phenolic resin. After introducing POSS into the resole, a comprehensive study is conducted to reveal the effects of POSS on the thermal degradation of phenolic resin. First, thermal degradation behaviors of neat phenolic resin and modified phenolic resin are carried out by thermogravimetric analysis (TGA). Then, the gas volatiles from thermal degradation are investigated by thermogravimetric mass spectrometry (TG-MS). Finally, the residues after thermal degradation are characterized by X-ray diffraction (XRD). The research indicates that POSS modified phenolic resin shows a better thermal stability than neat phenolic resin, especially at high temperatures under air atmosphere. On the one hand, the introduction of the POSS group can effectively improve the release temperature of oxygen containing volatiles. On the other hand, the POSS group forms silica at high temperatures under air, which can effectively inhibit the thermal oxidation of phenolic resin and make phenolic resin show a better high-temperature oxidation resistance. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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12 pages, 3285 KiB

Open AccessEditor’s ChoiceArticle

New Functionalized Ionic Liquids Based on POSS for the Detection of Fe³⁺ Ion

by Wensi Li and Shengyu Feng

Polymers 2021, 13(2), 196; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13020196 - 07 Jan 2021

Cited by 8 | Viewed by 2244

Abstract

This study reports a novel series of imidazolium ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSS) towards effective detection of metal ions, especially Fe3+ ion. ¹H, ¹³C, ²⁹Si NMR, high resolution mass spectra (HRMS) and Fourier transform infrared spectra [...] Read more.

This study reports a novel series of imidazolium ionic liquids (ILs) based on polyhedral oligomeric silsesquioxanes (POSS) towards effective detection of metal ions, especially Fe3+ ion. ¹H, ¹³C, ²⁹Si NMR, high resolution mass spectra (HRMS) and Fourier transform infrared spectra (FTIR) were applied to confirm the structures of the ILs based on POSS (ILs-POSS). The three ILs-POSS were synthesized via a green chemistry approach—a thiol-ene “click” reaction without metal ions as catalysts. Furthermore, the spherical vesicle structures of the ILs-POSS were observed and caused by self-assembly behaviors. Through comprehensive characterizations, these ILs-POSS have performed excellent thermal stabilities and low glass transition temperatures. In addition, we found it very meaningful that the limits of detection (LODs) of the three ILs-POSS for the detection of the Fe³⁺ ion were 7.91 × 10⁻⁸ M, 1.2 × 10⁻⁷ M, and 1.2 × 10⁻⁷ M, respectively. These data illustrate that these ILs-POSS have great potential for the detection of the Fe³⁺ ion. In conclusion, this study not only prepared novel ILs-POSS, but also provided new materials as fluorescent sensors in the detection of Fe³⁺. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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9 pages, 5661 KiB

Open AccessEditor’s ChoiceArticle

High Refractive-Index Hybrids Consisting of Water-Soluble Matrices with Bipyridine-Modified Polyhedral Oligomeric Silsesquioxane and Lanthanoid Cations

by Kazunari Ueda, Takahiro Kakuta, Kazuo Tanaka and Yoshiki Chujo

Polymers 2020, 12(7), 1560; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12071560 - 14 Jul 2020

Cited by 4 | Viewed by 2557

Abstract

We report high refractive-index (RI) films composed of polyhedral oligomeric silsesquioxane (SSQ) matrices and various lanthanoid cations. The SSQ matrices were constructed from octaammonium SSQ by connecting with bipyridine dicarboxylic acid, which is expected to capture cations. By modulating the feed ratio between [...] Read more.

We report high refractive-index (RI) films composed of polyhedral oligomeric silsesquioxane (SSQ) matrices and various lanthanoid cations. The SSQ matrices were constructed from octaammonium SSQ by connecting with bipyridine dicarboxylic acid, which is expected to capture cations. By modulating the feed ratio between SSQ and dicarboxylic acid, the series of the SSQ matrices were obtained with variable cross-linking ratios among the SSQ units. Thin transparent films were able to be prepared through the drop-casting method with the aqueous mixtures containing SSQ matrices and various kinds of lanthanoid salts up to 40 wt %. From RI measurements, it was revealed that the increase of the amount of the metal ion can significantly lift up the RI values. In particular, critical losses of Abbe numbers, which theoretically have the trade-off relationship toward increases in RI values, were hardly detected. This effect could be obtained by cation assembly in local spots that are assisted by SSQ. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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15 pages, 3999 KiB

Open AccessEditor’s ChoiceArticle

Preparation of Tri(alkenyl)functional Open-Cage Silsesquioxanes as Specific Polymer Modifiers

by Katarzyna Mituła, Michał Dutkiewicz, Julia Duszczak, Monika Rzonsowska and Beata Dudziec

Polymers 2020, 12(5), 1063; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12051063 - 06 May 2020

Cited by 7 | Viewed by 2830

Abstract

The scientific reports on polyhedral oligomeric silsesquioxanes are mostly focused on the formation of completely condensed T₈ cubic type structures and recently so-called double-decker derivatives. Herein, we report on efficient synthetic routes leading to trifunctionalized, open-cage silsesquioxanes with alkenyl groups of varying [...] Read more.

The scientific reports on polyhedral oligomeric silsesquioxanes are mostly focused on the formation of completely condensed T₈ cubic type structures and recently so-called double-decker derivatives. Herein, we report on efficient synthetic routes leading to trifunctionalized, open-cage silsesquioxanes with alkenyl groups of varying chain lengths from -vinyl to -dec-9-enyl and two types of inert groups (iBu, Ph) at the silsesquioxane core. The presented methodology was focused on hydrolytic condensation reaction and it enabled obtaining titled compounds with high yields and purity. A parallel synthetic methodology that was based on the hydrosilylation reaction was also studied. Additionally, a thorough characterization of the obtained compounds was performed, also in terms of their thermal stability, melting and crystallization temperatures (TGA and DSC) in order to show the changes in the abovementioned parameters dependent on the type of reactive as well as inert groups at Si-O-Si core. The presence of unsaturated alkenyl groups has a profound impact on the application potential of these systems, i.e., as modifiers or comonomers for copolymerization reaction. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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13 pages, 6593 KiB

Open AccessArticle

A Novel Acetylene-Functional/Silicon-Containing Benzoxazine Resin: Preparation, Curing Kinetics and Thermal Properties

by Qilin Mei, Honghua Wang, Danliao Tong, Jiuqiang Song and Zhixiong Huang

Polymers 2020, 12(5), 999; https://doi.org/10.3390/polym12050999 - 26 Apr 2020

Cited by 8 | Viewed by 2897

Abstract

Benzoxazine resin has been paid more attention in the fields of aviation, electronics, automobiles and new energy industries because of its excellent comprehensive performance. Further application is limited, however, by shortcomings such as high brittleness and high curing temperature. Furthermore, higher thermal stability [...] Read more.

Benzoxazine resin has been paid more attention in the fields of aviation, electronics, automobiles and new energy industries because of its excellent comprehensive performance. Further application is limited, however, by shortcomings such as high brittleness and high curing temperature. Furthermore, higher thermal stability is imperiously demanded in special areas. Incorporating both an acetylene group and silicon into the benzoxazine monomer is a promising possible solution to improve the curing processability, thermal properties and toughness of benzoxazine. In this paper, an acetylene-functional/silicon-containing benzoxazine monomer was prepared by two-step synthesis, and acetylene-functional benzoxazine was also prepared as a comparison. FTIR and ¹H NMR confirmed the molecular structure of acetylene-functional/silicon-containing benzoxazine. Differential scanning calorimetry (DSC) analysis showed that the initial and peak degradation temperatures of acetylene-functional/silicon-containing benzoxazine were decreased by 21 °C and 18 °C compared with acetylene-functional benzoxazine, respectively. The apparent activation energy of the curing reaction of acetylene-functional/silicon-containing benzoxazine was 83.1 kJ/mol, which was slightly lower than acetylene-functional benzoxazine (84.7 kJ/mol). TGA results showed that the acetylene-functional/silicon-containing benzoxazine had a higher thermal stability than acetylene-functional benzoxazine. The temperatures of 5% weight loss of acetylene-functional/silicon-containing benzoxazine were 380 °C in nitrogen and 485 °C in air, and the char yield at 1000 °C was 80% in nitrogen and 21% in air, respectively. The results of mechanical properties showed that the impact strength of acetylene-functional/silicon-containing benzoxazine was higher than acetylene-functional benzoxazine by 35.4%. The tensile and flexural strengths of acetylene-functional/silicon-containing benzoxazine were slightly higher than that of acetylene-functional benzoxazine. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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19 pages, 2561 KiB

Open AccessArticle

Hyperbranched Poly(ether-siloxane)s Containing Ammonium Groups: Synthesis, Characterization and Catalytic Activity

by Paweł G. Parzuchowski, Aleksandra Świderska, Marlena Roguszewska, Karolina Rolińska, Dominik Wołosz and Mariusz Mamiński

Polymers 2020, 12(4), 856; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12040856 - 07 Apr 2020

Cited by 2 | Viewed by 3698

Abstract

In this article we report an easy synthetic route towards hyperbranched polyglycerols (Amm-HBPGs) containing trimethylammonium groups and siloxane or hydroxyl end-groups. Siloxane derivatives of Amm-HBPGs were synthesized in an efficient five-step procedure including an anionic ring opening copolymerization of the phthalimide-epoxy monomer with [...] Read more.

In this article we report an easy synthetic route towards hyperbranched polyglycerols (Amm-HBPGs) containing trimethylammonium groups and siloxane or hydroxyl end-groups. Siloxane derivatives of Amm-HBPGs were synthesized in an efficient five-step procedure including an anionic ring opening copolymerization of the phthalimide-epoxy monomer with glycidol, followed by reactions with allyl bromide, hydrosililation with hydrogenheptamethyltrisiloxane, hydrazinolysis of phthalimide groups and quaternization of resulting amine groups with methyl iodide. Hydroxyl derivatives were obtained by quaternization of previously reported aminated HBPG’s with methyl iodide. Polymeric products were characterized using various NMR techniques, FTIR, and elemental analysis. Both Amm-HBPGs were shown to be effective in catalysis of addition of CO₂ to oxirane. The hydrophilic catalysts showed higher efficiency but synthesis of ethylene carbonate was accompanied by formation of small amounts of ethylene glycol. The siloxane-containing catalyst was easily separable from reaction mixture showing high potential in the process of converting carbon dioxide into valuable chemical raw materials. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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10 pages, 2823 KiB

Open AccessArticle

Study of POSS on the Properties of Novel Inorganic Dental Composite Resin

by Jiahui Wang, Yizhi Liu, Jianxin Yu, Yi Sun and Weili Xie

Polymers 2020, 12(2), 478; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12020478 - 20 Feb 2020

Cited by 17 | Viewed by 3184

Abstract

Various amounts of methacryl polyhedral oligomeric silsesquioxane (POSS) were explored to be incorporated into novel nano SiO₂ dental resin composites using light curing method. The scanning electron microscopy (SEM), optical microscopy, fourier transform infrared spectroscopy (FTIR), nanoindentation, nanoscratch and three-point flexure tests [...] Read more.

Various amounts of methacryl polyhedral oligomeric silsesquioxane (POSS) were explored to be incorporated into novel nano SiO₂ dental resin composites using light curing method. The scanning electron microscopy (SEM), optical microscopy, fourier transform infrared spectroscopy (FTIR), nanoindentation, nanoscratch and three-point flexure tests were performed. The volumetric shrinkage and mechanical properties such as hardness, elastic modulus, resistance, flexural strength and fracture energy were analyzed. With the additions of POSS, the volume shrinkage decreased and the mechanical properties initially increased. The effects of POSS on these properties were studied to provide a reference for clinically selecting a composite resin with excellent properties. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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15 pages, 4587 KiB

Open AccessArticle

Main Chain–Type Block Copolymers through Atom Transfer Radical Polymerization from Double-Decker–Shaped Polyhedral Oligomeric Silsesquioxane Hybrids

by Wei-Cheng Chen, Yu-Hsuan Tsao, Chih-Feng Wang, Chih-Feng Huang, Lizong Dai, Tao Chen and Shiao-Wei Kuo

Polymers 2020, 12(2), 465; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12020465 - 17 Feb 2020

Cited by 12 | Viewed by 3455

Abstract

In this study, we synthesized two main chain–type block copolymers featuring hydrogen bond donor and acceptor segments through atom transfer radical polymerization (ATRP) using a bifunctionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the initiator. Hydrosilylation of vinylbenzyl chloride at the two corners of [...] Read more.

In this study, we synthesized two main chain–type block copolymers featuring hydrogen bond donor and acceptor segments through atom transfer radical polymerization (ATRP) using a bifunctionalized polyhedral oligomeric silsesquioxane (POSS) nanoparticle as the initiator. Hydrosilylation of vinylbenzyl chloride at the two corners of a double-decker silsesquioxane (DDSQ) provided the bifunctionalized benzyl chloride initiator VBC-DDSQ-VBC, which we applied as a platform to prepare a main chain–type polystyrene homopolymer (PS-DDSQ-PS), the diblock copolymer poly(styrene–b–4-vinylpyridine) (P4VP-b-PS-DDSQ-PS-b-P4VP), and the diblock copolymer poly(styrene–b–tert-butoxystyrene) (PtBuOS-b-PS-DDSQ-PS-b-PtBuOS) through sequential ATRP. Selective hydrolysis of the tert-butoxyl units of PtBuOS-b-PS-DDSQ-PS-b-PtBuOS yielded the strongly hydrogen bonding diblock copolymer poly (styrene-b-vinylphenol) (PVPh-b-PS-DDSQ-PS-b-PVPh). We used Fourier transfer infrared spectroscopy, nuclear magnetic resonance spectroscopy, size exclusion chromatography, differential scanning calorimetry, mass-analyzed laser desorption ionization mass spectrometry, and transmission electron microscopy to investigate the chemical structures, thermal behavior, and self-assembled nanostructures formed by these main chain–type block copolymers based on DDSQ. Full article

(This article belongs to the Special Issue Silsesquioxane (POSS) Polymers, Copolymers and Nanoparticles)

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